Cylinder bores located in the cylinder blocks of internal combustion engines may experience a significant tribological load, e.g., friction and wear, due to the sliding, linear motion of pistons therein. Furthermore, especially in diesel processes which may have lower combustion temperatures, thermal energy may be lost in the combustion cycle due to lack of thermal insulation in the cylinders to retain the thermal energy.
One example to address wear from friction is to produce metallic layers by thermal spray or plasma powder spray.
However, the inventors herein have recognized potential issues with such systems. One such issue is that there is not a cost-effective technique of applying thermal spray to a cylinder block comprising cast gray iron, for example, because of the need for a costly NiAl adhesive base. Further, current thermal spraying methods involve high velocity and high temperature treatment methods that may change material properties and may produce layers of continuous porosity which undergo corrosion through the infiltration of iron oxides, for example. Plasma spray coatings are based on Fe-material and do not have a thermal barrier effect. Further, layers produced by plasma powder spraying may not withstand the tribological and mechanical load present within a cylinder of an internal combustion engine, as the structures thereof may contain micro-cracks.
One potential approach to at least partially address some of the above issues includes a system and method of coating a cylinder bore. This method includes producing a cylinder body present in a blank, drilling out a bore and pre-machining the bore, applying an enamel coating to an inner surface of the bore, and, post-treating the coated bore, the enamel coating bonding to the base material of the bore metallurgically by phase formation. In one example, the enamel coating may be applied via a rotating apparatus or a floating apparatus.
In another example, the enamel coating is applied to a cast gray iron cylinder block, which may undergo heat treatment to bond the enamel coating and convert the cast gray iron to an austempered gray iron. In this way, a cylinder block is produced with improved mechanical properties and a cylinder bore is coated with an enamel coating which is corrosive resistant, reduces wear and friction, and provides thermal insulation in order to reduce the loss of thermal energy in the combustion cycle.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.